Illumination based on semiconductor light sources, such as light-emitting diodes (LEDs), offers an efficient and long-lived alternative to fluorescent, high-intensity discharge and incandescent lamps. Many LED light sources employ high powered LEDs, which pose thermal management problems and other related problems. Another drawback with state of the art LED devices is their high initial cost.
Small semiconductor dice including those with sizes of 300 um or smaller provide numerous benefits in applications such as broad area lighting, concentrator photovoltaics and electronics. Devices of this scale cannot be transferred from a source wafer to a target substrate utilizing conventional pick and place technology. One technique is transfer printing, for example using composite patterning devices comprising a plurality of polymer layers each having selected values of mechanical properties, such as Young's Modulus and flexural rigidity; selected physical dimensions, such as thickness, surface area and relief pattern dimensions; and selected thermal properties, such as coefficients of thermal expansion and thermal conductivity; to provide high resolution patterning on a variety of substrate surfaces and surface morphologies.
There is therefore a need for an innovation whereby small semiconductor dice can be efficiently and effectively transferred from a host substrate to a target substrate.